This removes libnm-glib, libnm-glib-vpn, and libnm-util for good.
The it has been replaced with libnm since NetworkManager 1.0, disabled
by default since 1.12 and no up-to-date distributions ship it for years
now.

Removing the libraries allows us to:

* Remove the horrible hacks that were in place to deal with accidental use
  of both the new and old library in a single process.
* Relief the translators of maintenance burden of similar yet different
  strings.
* Get rid of known bad code without chances of ever getting fixed
  (libnm-glib/nm-object.c and libnm-glib/nm-object-cache.c)
* Generally lower the footprint of the releases and our workspace

If there are some really really legacy users; they can just build
libnm-glib and friends from the NetworkManager-1.16 distribution. The
D-Bus API is stable and old libnm-glib will keep working forever.

https://github.com/NetworkManager/NetworkManager/pull/308

We need this for a little little longer :(

This reverts commit 1de8383ad9fdfc8f552117e5d109bdfa7005634b.

This removes libnm-glib, libnm-glib-vpn, and libnm-util for good.
The it has been replaced with libnm since NetworkManager 1.0, disabled
by default since 1.12 and no up-to-date distributions ship it for years
now.

Removing the libraries allows us to:

* Remove the horrible hacks that were in place to deal with accidental use
  of both the new and old library in a single process.
* Relief the translators of maintenance burden of similar yet different
  strings.
* Get rid of known bad code without chances of ever getting fixed
  (libnm-glib/nm-object.c and libnm-glib/nm-object-cache.c)
* Generally lower the footprint of the releases and our workspace

If there are some really really legacy users; they can just build
libnm-glib and friends from the NetworkManager-1.16 distribution. The
D-Bus API is stable and old libnm-glib will keep working forever.

https://github.com/NetworkManager/NetworkManager/pull/308

Add missing trailing commas that avoids getting noise when another
file/parameter is added and eases reviewing changes[0].

[0] https://gitlab.gnome.org/GNOME/dconf/merge_requests/11#note_291585

Apparently vapigen can't find the NetworkManager-1.0.gir belonging to
libnm-util.vapi.

(cherry picked from commit 44f14e969bd4bf56efac28d01c0f9823abee0e5c)

The strings holding the names used for libraries have also been
moved to different variables. This way they would be less error
as these variables can be reused easily and any typing error
would be quickly detected.

meson is a build system focused on speed an ease of use, which
helps speeding up the software development. This patch adds meson
support along autotools.

[thaller@redhat.com: rebased patch and adjusted for iwd support]

https://mail.gnome.org/archives/networkmanager-list/2017-December/msg00022.html